An ever-increasing number of manufacturers are adopting integrated modular software architectures into their products. This type of software architecture generally refers to distributed, real-time (that is, switched) computer networks within a product or system. A typical switched network will consist of several computing modules capable of supporting numerous applications. Each application, in turn, is considered to have varying degrees of safety criticality levels. A typical integrated modular software architecture uses a layered approach to allow for hardware and software transparency. Software code re-use and portability is also an important feature. These architectures are designed such that one or more applications can be inserted or altered with minimum impact on other applications and their supporting safety features. In addition, the switched networks have a built-in capability to operate in the presence of a failure, allowing for periods of maintenance-free operation.
Traditionally, measuring jitter has been critical to determining the performance of switched networks such as the one described above. As the data rates of switched networks continue to increase, reducing jitter becomes an even higher priority for ensuring a high level of reliability. A standard definition of jitter is “the deviation of a timing event of a signal from its ideal position.” Jitter affects the network as a whole, and can be introduced by every network element used to generate, convey and receive communication signals within the network. In defining fault-tolerant aspects for network architectures, various networking communications standards will mandate that the jitter of a periodic packet stream leaving an end system (that is, a processor transmitting data packets into the switched network) be tightly constrained. Traditional switched network scheduling methods that place the data packets in a typical data queue will only meet these tights constraints at low traffic loads without introducing significant jitter into the network.